PT scanning position on the Pre-load

When this preferred job was first implemented, a bid sheet was put up and went by seniority as to who signed up/got the position. Once that was determined, said person wasn't ever taken from that position and then put on the belt to load trucks due to being shorthanded or injuries(light duty work work)

A long time scanner lost his job about 3mos ago and that preferred position hasn't been put up for bid, but the pre-loader with the most seniority has been doing it. Problem is, is that he's been taken away from scanning on numerous occasions whether it be for others having injury issues or shorthanded to where the Sup does the scanning and he get's moved to loading.

Shouldn't the bid sheet been put up already? Is the company purposely not putting one up so that person can be moved from that job at will? Is it something that should be brought up to the teamster rep?